Radiation curable coating compositions and process for the preparation thereof

ABSTRACT

A COATING COMPOSITION USEFUL FOR RADIATION CURING IS PREPARED THROUGH COPOLYMERIZATION OF A MIXTURE COMPRISING A VINYL MONOMER HAVING A HYDROXYL GROUP AND A,B-ETHYLENICALLY UNSATURATED CARBOXYLIC ESTER OF A MONOHYDRIC ALCOHOL, PRIMARY ESTERIFICATION OF THE HYDROXYL GROUP OF THE RESULTANT COPOLYMER WITH A POLYHYDRIC CARBOXYLIC ANYHYDRIDE IN AN ORGANIC SOLVENT, AND SECONDARY ESTERFICATION AND/OR ETHERFICATION OF CARBOXYLIC GROUP AND/OR HYDROXYL GROUP OF THE PRIMARILY ESTERFIED COPOLYMER WITH A EPOXY VINYL MONOMER. THE COATING COMPOSITION MAY FURTHER CONTAIN POLYMERIZABLE AND/OR CROSS-LINKAGE FORMABLE COMPOUNDS ACTIVE FOR RADIATION CURING, THE EXAMPLE, A COMPOUND OF THE FRMULA:   CH2=C(-R10)-COO-R9-O-(CO-R8-COO-R9-O)L-CO-C(-R10)=CH2   WHEREIN R8 IS A DIVALENT GROUP HAVING 2 TO 100, R9 IS A SATURATED DIVALENT HYDROCARBON GROUP OF 2 TO 10C, R10 IS HYDROGEN ATOM OR METHYL GROUP AND 1 IS 0 OR 1 TO 10

United States Patent Ofiice 3,754,054 Patented Aug. 21, 1973 3,754,054 RADIATION CURABLE COATING COMPOSI- TIONS AND PROCESS FOR THE PREPARA- TION THEREOF Tadasu Kimura, Otake-shi, Hiroyuki Harada, Tokyo, and Juichi Kobayashi and Hideo Nakamoto, Otake-shi, Japan, assignors to Mitsubishi Rayon Company Limited, Tokyo, Japan No Drawing. Filed Dec. 15, 1969, Ser. No. 885,272 Claims priority, application Japan, Dec. 23, 1968, 43/93,725 Int. Cl. B01j 1/10; C08f 27/12; C08g 39/10 16 Claims ABSTRACT OF THE DISCLOSURE A coating composition useful for radiation curing is prepared through copolymerization of a mixture comprising a vinyl monomer having a hydroxyl group and a,;8-ethylenically unsaturated carboxylic ester of a monohydric alcohol, primary esterification of the hydroxyl group of the resultant copolymer with a polyhydric carboxylic acid anhydride in an organic solvent, and secondary esterification and/or etherification of carboxylic group and/or hydroxyl group of the primarily esterified copolymer with an epoxy vinyl monomer. The coating composition may further contain polymerizable and/or cross-linkage formable compounds active for radiation curing, for example, a compound of the formula:

wherein R is a divalent hydrocarbon group having 2 to 10C, R is a saturated divalent hydrocarbon group of 2 to 10C, R is hydrogen atom or methyl group and l is O or 1 to 10.

The present invention relates to a coating composition which is valuable for obtaining film coatings having excellent coating features by radiation curing of radioactive energy such as electron beams, and ultra-violet rays and a process for preparing the composition.

Recently, based upon development of a charged particle accelerator, especially, a low volage, large power electron accelerator, a method for radioactively curing a film coating applied on a base material surface by action of electron beams has received public attention. Such public interest is based on the following:

(I) the radiation curing of film coating is completed at an ambient temperature without a heating operation in a time shorter than that of the heat-curing, and

(2) the radioactively cured film coatings have coating properties equal to or superior to those of the heatcured film coatings.

The principle of the radiation curing method for film coating involves the inclusion of polymerizable components in the coating composition, having ethylenically unsaturated groups which are cured and interor intramolecularly cross-linked by effect of the radioactive energy so as to form insoluble and infusible coatings. It is well-known that the conventional coating materials containing an unsaturated polyester resin and an ethylenically unsaturated monomer are usable for a radiation curing process utilizing the action of electron beams. The conventional coatings cured by the radiation curing method have good coating properties but have some disadvantages such as insufficient weathering resistance, unsatisfactory adhesiveness to a base material surface or insufiieient flexibility. Further, the above stated coating materials tend to form some inner stresses in the cured film coating owing to cross-linking between the componental molecules due to the eliect of the electron beams, especially at a high dose rate thereof. If such shrinking occurs in the curing process, the resultant film coating has some stresses due to the shrinking. Such stresses produced in the film coating causes insufiicient impact resistance, adhesiveness to a base material surface, flexibility and other inferior coating properties.

As one of the coating compositions capable of radiation curing with radioactive energy which is different from the above-stated coating composition mainly containing the unsaturated polyester resin, a coating composition containing a prepolymer of the formula:

wherein R is hydrogen atom or lower alkyl group, is known. The above-stated prepolymer is prepared by addition reaction between a base polymer having glycidyl group, of the formula:

and an a,;3-ethylenically unsaturated carboxylic acid. However, the prepolymer has the disadvantage that the glycidyl group in the base polymer tends to cross-link intramolecularly and/or intermolecularly during the ad dition reaction and the cross-linking causes gelation of the coating composition. Especially, if a polymerizable monomer such as a vinyl monomer is used for dissolving the prepolymer, the above-stated tendency becomes very apparent. Further, the prepolymers disadvantage is such that, the prepolymer is unsatisfactory for obtaining a film coating having high stifiness, high adhesiveness and other desirable coating properties. The disadvantage is caused by insufiicient relaxation of the inner stress in the film coating during radiation curing and the insuflicient relaxation is due to unsuilicient length of the pendent chain which is grafted to the base polymer and is eiiective for forming the cross-links.

Also, one of the well-known coating compositions usable for the radiation curing method is a coating composition containing a prepolymer of the unit formula:

The prepolymer is prepared by addition reaction between a polymer having a carboxyl group and of the unit formula:

and a vinyl monomer having a glycidyl group. However, the prepolymer is unsatisfactory for obtaining a sufficient coated film due to the same reasons as described above. Also, coating compositions mainly containing polymerizable unsaturated compound such as condensation product of a polyol and an unsaturated carboxylic acid, and an addition product of epoxy resin and an a,/3-ethylenically unsaturated carboxylic acid are known. However, these compositions are also insufiicient for obtaining desirable film coating due to the same reasons.

An object of the present invention is to provide a coating composition which is easily cured by radiation of radioactive energy such as electron beams and ultra-violet rays and is efiective for forming a film coating having coating properties of the same degree as those of the film coating of the conventional thermosetting resin but not having the disadvantages as stated above.

Another object of the present invention is to provide a process for preparing the coating composition as stated above.

The coating composition of the present invention comprises a prepolymer effective for radiation curing and comprising the following componental units:

(1) a base copolymer having an average molecular weight of 1,000 to 100,000 and consisting of the following polymerization units:

(A) at least one vinyl monomer having a hydroxyl group, and

(B) at least one a,B-ethylenically unsaturated carboxylic ester of a monohydric alcohol having -1 to 18 carbon atoms;

(2) at least one pendent polyhydric carboxylic acid residue unit attached to the base copolymer and primarily esterifying at least 10% by mol of the hydroxyl group of the base copolymer with carboxyl group thereof, and

(3) at least one pendent epoxy vinyl monomeric residue unit attached to the first esterified base copolymer and secondarily esterifying and/ or etherifying at least 10% by mol of a total content of the hydroxyl group and carboxyl group of the first esterified base copolymer with epoxy groups thereof.

Preferably, the base copolymer in the prepolymer consists of 1 to 50% by weight of the unit A and 50 to 99% by weight of the unit B.

The preparation process of this coating composition comprises the following steps:

(1) Preparation of the base copolymer A mixture containing 1 to 50% by weight of at least one kind of vinyl monomer having a hydroxyl group and 50 to 99% by weight of at least one kind of aJJ-ethylenically unsaturated carboxylic ester of a monohydric alcohol having 1 to 18 carbon atoms is copolymerized into a base copolymer having an average molecular weight of 1,000 to 100,000.

(2) Primary esterification A polyhydric carboxylic acid anhydride is contacted with the base copolymer dissolved in an organic solvent in a mixing ratio of at least 0.1 mol with respect to the 1 mol of the hydroxyl group of the base copolymer in order to esterify the hydroxyl group of the base copolymer with the acid anhydride.

(3) Secondary esterification and/or etherification An epoxy vinyl monomer is contacted with the primarily esterified base copolymer in the organic solvent in a. mixing ratio of at least 0.1 mol with respect to 1 mol of a total of the hydroxyl group and carboxyl group of the primarily esterified base copolymer in order to secondarily esterify and/or etherify the hydroxyl group and/ or carboxyl group of the primarily esterified base copolymer with the epoxy group of the epoxy vinyl monomer.

The base copolymer may be prepared by way of a solution polymerization, suspension polymerization, precipitation polymerization or bulk polymerization.

The unit A of the base copolymer may be selected from the vinyl monomers having a hydroxyl group of the Formulas I, II and III:

oH d-o-o-R-h-R O -o-m in which R R and R represent a hydrogen atom or methyl group, R represents in which R represents a hydrogen atom or methyl group and n represents an integral number of 1 to 10, R represents a hydrogen atom or alkyl group of 1 to 12 carbon atoms, and m represents an integral number 1 or 2; allyl alcohol; methallyl alcohol; hydroxyalkyl acrylamide and hydroxyalkyl methacrylamide. The compounds of the Formula I concretely include the compounds as indicated below.

The compounds of the Formula II concretely include mono-( 2 hydroxyethyl) itaconate, methyl-( 2 hydroxyethyl) itaconate and (2-hydroxyethyl)-a-methylene glurarate. Also, the compounds of the Formula III concretely include mono-(2-hydroxyethyl) maleate, methyl-(Z-hydroxypropyl) maleate, butyl-(Z-hydroxyethyl) maleate and octyl-(2-hydroxypropyl) maleate. The unit A may be contained in the base copolymer in a content of 1 to 50% by weight. Preferably 15 to 50% by weight. If the content of the unit A is less than 1%, the prepolymer prepared from the base copolymer has low sensitivity to radiation curing. On the other hand, if the content of the unit A is more than 50%, the resultant film coating is brittle whereas the sensitivity to radiation curing thereof is satisfactory.

The unit B in the base copolymer may be selected from esters obtained from a,B-ethylenically unsaturated carboxylic acid such as acrylic acid, methacrylic acid, itaconic acid and a-rnethylene glutaric acid and monohydric alcohol having 1 to 18 carbon atoms such as straight or branched aliphatic monohydric alcohol of l to 18 carbon atoms, cyclohexanol, phenol, benzyl alcohol, phenethyl alcohol, ethylene glycol mono-lower alkyl ether. The content of the unit B in the base copolymer is required to be 50 to 99% by Weight, because, the base copolymer comprising the unit B is effective with respect to activation by radiation energy and thus for forming cross-links, and a coating composition containing a prepolymer comprising the unit B results in a film coating having an excellent weathering resistance and high chemicaLresistance.

The polyhydric carboxylic acid anhydride to be attached initially to the base copolymer is selected from saturated and unsaturated carboxylic acid anhydrides having at least two carbonyl groups, for example, maleic acid anhydride, chlorinated maleic acid anhydride, succinic acid anhydride, itaconic acid anhydride, oc-rnethylene glutaric acid anhydride, citraconic acid anhydride, phthalic acid anhydride, tetrahydrophthalic acid anhydride, hexahydrophthalic acid anhydride, naphthalene dicarboxylic acid anhydride, dodecyl succinic acid anhydride and 1,4,5,6,7,7-hexachloro-bi-cyclo-[2,2,1]hept-6- en-2,3-dicarboxylic acid anhydride. These polyhydric carboxylic acid anhydrides are elfective for preventing the film coating from shrinking during radiation curing. If an unsaturated polyhydric carboxylic acid anhydride is used as a first esterifying agent, it is also elfective as a crosslinking agent by radiation curing. The polyhydric carboxylic acid anhydride should be attached to the base copolymer so as to esterify at least by mol of the hydroxyl group of the base copolymer with the carboxyl group thereof. If the esterification ratio is less than 10% by mol, the resultant prepolymer has a low sensitivity to radiation curing. However, the polyhydric carboxylic acid anhydride may be mixed into the esterification system at a mixing ratio larger than 1.0 mol with respect to 1 mol of the hydroxyl group of the base copolymer.

The epoxy vinyl monomer to be attached secondarily to the base copolymer may be selected from a,B-ethylenically unsaturated carboxylic esters of epoxy alkyl compounds such as glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, methallyl glycidyl ether and vinyl cyclohexane monoxide, and glycidyl ethers of a vinyl monomer having a hydroxyl group.

The epoxy vinyl monomer should be attached to the initially esten'fied base copolymer so as to esterify and/ or etherify at least 10% by mol of a total content of the hydroxyl group and carboxyl group of the initially esterified base copolymer with the epoxy group thereof. If the esterification and/or etherification ratio is less than 10% by mol, the resultant prepolymer has a low sensitivity to radiation curing. However, the mixing ratio of the epoxy vinyl monomer may be larger than 1.0 mol with respect to 1 mol of the total content of the hydroxyl group and the carboxyl group of the firstly esterified base copolymer.

The prepolymer according to the present invention has the following advantages:

(1) easy preparation, because the primary esterification and secondary esterification and/or etherification are quantitatively and easily carried out,

(2) rapid curing by radioactive energy, and

(3) superior features of resultant film coating.

For example, a prepolymer prepared from maleic acid anhydride as a first esterification agent and glycidyl acrylate as a second esterifying and/or an etherifying agent has a pendent unit of the formula:

-OH,-oH-

CCH=CH-C-O-OH -OH-CH -O-C-CH II I ll and has a radiation sensitiveness higher than that of the conventional prepolymer, owing to a long pendent group grafted to the base copolymer and having an active double bond at an end thereof.

Further, the prepolymer stated above forms a three dimensional structure by the cross-linking reaction between active radicals produced in the prepolymer by effect of electron beams and the double bonds of the pendent group with high rapidity. Therefore, the coating composition containing this prepolymer can be rapidly gelled by radiation curing.

The prepolymer, according to the present invention, further has an advantage that due to the long pendent group having a polymerizable double bond at an end thereof, the prepolymer does not result in any undesirable shrinking in the film coating during radiation curing, and thus, results in a film coating having no inner stress.

The first esterification and the second esterification and/ or etherification may be carried out under a non-catalyst condition. However, it is desirable that these reactions be completed within a short time at a relatively lower temperature in consideration of the desired features of the resultant film coating. For this purpose, use of a basic catalyst is very effective. Vinyl monomers having a tertiary amine group are especially effective for accelerating these reactions without any undesirable side-reactions and have no undesirable effect on the properties of resultant film coating. The tert-amine catalyst may be selected from compounds of the Formula IV:

I R VI wherein R represents a hydrogen atom or methyl group, R and R represent a methyl or ethyl group, respectively, and p represents an integer of 1 or 2, for example, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, N-dimethyl acrylamide, N-dimethyl methacrylamide, 2-vinyl pyridine, 2-methyl-5-vinyl pyridine, 3-ethyl-5-vinyl pyridine, 5-butyl-2-vinyl pyridine and the like. These catalytic compounds may be added into each reaction system of the first and second esterifications. Particularly, dimethylaminoethyl acrylate or methacrylate are very effective for these reactions.

Also, these catalysts may be comprised in the base copolymer as a polymerization unit. Such a base copolymer is effective for accelerating the esterifications and decreasing the side-reactions during the esterifications.

The catalyst is added into a prepolymer preparing system in a range from 0.5 to 20% based on the weight of the base copolymer. Addition of the catalyst in a range less than 0.5% by weight causes an insufiicient esterification and/or etherification of the base copolymer, but, addition of the catalyst in a range larger than 20% by weight results in an undesirable colored coating composition. Usually, the first esterification and the second esterification and/or etherification of the base copolymer are carried out under conditions wherein a base copolymer is dissolved in an organic solvent in a content of 10 to by weight. Toluene, xylene, acetone, methylethyl ketone, methyl-isobutyl ketone, ethylacetate, butyl acetate, diisobutyl ketone, acetic ester of ethylene glycol monoethyl ether, are usable for the purpose. Particularly, it is most preferable that the base copolymer be dissolved in a vinyl compound which can be radically polymerized by radiation of radioactive energy and can dissolve or microfinely disperse the resultant prepolymer from the base copolymer. In such a case, since the coating comopsition containing this vinyl compound as the solvent can be solidified entirely by radiation energy, loss of the solvent does not occur during the radiation curing. Therefore, the coating composition containing a polymerizable solvent is economically valuable.

The polymerizable solvent may be selected from ethylenically unsaturated carboxylic esters of monohydric alcohol having 1 to 18 carbon atoms, such as acrylic esters and methacrylic esters of monohydric alcohol such as methanol, ethanol, butanol, isobutyl alcohol, 2-ethylhexanol, benzyl alcohol, cyclohexanol and phenethyl alcohol, ethyleneglycol monoalkyl ether, propylene glycol monoalkyl ether and esters of the Formula V:

wherein R represents a hydrogen atom or lower alkyl (d) Saturated polyhydric carboxylic acids group. Also, the polymerizale solvent may be selected from vinyl monomers which are liquid at room temper- The group includes succinic acid, adipic acid, sebacic attire, uch as triallyl isocyanurate, ethylene glycol diacid, phthalic acid, isophthalic acid, terephthalic acid, methacrylate and diallyl phthalate. In consideration of 2,5-dimethyl terephthalic acid, thiovalerianic acid, trithe desired film coating features of the film, it is prefermellitic acid, tetrahydrophthalic acid, hymic acid (3,6- able that the polymerizable solvent, particularly, acrylic endomethylene-n -phthalic acid), diglycollic acid, dodeesters or methacrylio esters, be contained in the coating cyl succinic acid and the like. These carboxylic acids are composition in a content of at least 30% by weight. converted into polymerizable compounds in the second The coating composition of the present invention may esterification and/or etherification step. For example, sucbe prepared by a process in which the first esterification cinic acid is converted into a compound of the formula: CH =CCOH -OHOH O--GCH CH,OO-OH CHCH OCO=CH,

H. t) 5H i) ii OH H.

and the second esterification and/or etherification are in the second system. carried out in a reaction system containing a base copoly- The compounds as stated above are very active with mer and a solvent containing 2 to 80% of the followrespect to polymerization by means of radiation energy ing compounds (a), (b), (c) or (d) based on a total owing to at least two double bonds therein. Further, the weight of the solvent. Such a process is valuable for procompounds can easily copolymerize with the prepolymer ducing a coating composition very active with respect to in the coating composition. Therefore, the coating comradiation energy, and for obtaining a film coating having position containing the polymerizable compound has a excellent coating feamres. high curing property and a high gelation etfect.

Furthermore, since the polymerizable compounds are liquid and have a low volatility at room temperature, This group is inclusive of the compounds of the Forthey can be easily handled compared with other vinyl (a) Vinyl monomers having a hydroxyl group mulas I, -II and III. For example, the coating composition monomers. prepared using a solvent containing Z-hydroxyethyl meth- Usually, these polymerizable compounds are prepared acrylate, maleic acid anhydride as a first esterifying agent during the prepolymer preparing process. But, the polymand glycidyl methacrylate as a second esterifying agent, erizable compound may be prepared in an individual reaccontains a prepolymer having a pendent unit of the tion system and then mixed into the coating composition. formula: Also, compounds of the Formula VI:

-CHCH-- OH: R" 0 R10 8 2% 0$7CH=CH%O-CH;-(EHCH O-fi GH, CH OR0-fiR -(!3O-R0C =(JH,

O O OH O \0 ti) )1 VI and a polymerizable compound having a low molecular wherein R represents a divalent hydrocarbon group havweight of the formula: ing 2 to 10 carbon atoms, R represents a saturated dioH,=o--o-o-oH2CH2-0OoH=CH-o-0-CH,-oH-C1Loo-o=0H,

H3 0 H 0 H5 (b) 'Polyhydric alcohols having at least two valent hydrocarbon having 2 to 10 carbon atoms, R

hydroxyl groups represents hydrogen atom or methyl group and l represeats 0 or an integer of 1 to 10, are usable for the coat- Th s group includes ethylene glycol, propylene gly ol, 5 ing composition of the present invention. 2,2- une hyl-L3-pr0p n diOI, 1,3-bl1tane (1101, The coating compositions containing the compounds of decane diol and the like the Formula VI can be easily cured by radiation energy If a coating composition 18 prepared using a solvent and the resultant film coatings have excellent features. containing ethylene glycol, the resultant coating compo- The compounds of the Formula VI in which I is 1, sition contains a compound having active double bonds, r may be prepared by the following processes (1), (2) of the formula: and (3). CH =C-(0CH (|1HCH O-fiCH=CHfiOCH OH;O?CH=CH?-OCH;CHCH O-OC=CH,

Ha 0 0H 0 o 0 on 0 H3 (c) Unsaturated carboxylic acids 1 0:0 This group includes a,18-ethylen1cally unsaturated carboxylic acids such as acrylic acid, methacrylic acid, ita- Rm O conic acid, and a-methylene glutaric acid, maleic acid, A ll 0:0 CH COR OH fumaric acid and acids of the formulas:

HOOC-CH=OHCOCHzGOCHgCH COOH and These carboxylic acids do not react with any unsaturated Rm 0 carboxylic acid anhydride being contained in the first E CH esterification system, but produce polymerizable com- CHFO- C O RO Q .C RB. Q OH pounds in the second esterification and/or etherification R10 0 O m in the second system.

. Minna! g g among on- R -on 310 0 0 0 0 R l t 6' 5 cm: o-R -o- -RB ORPO :CH; The compound of the formula:

may be selected from the same group illustrated hereinbefore as compounds of Formula I. Also, the compound of the formula:

C=O m o oo may be selected from the same group illustrated hereinbefore as the first esterifying agents, particularly, maleic acid anhydride, itaconic acid anhydride, ot-methylene glutaric acid anhydride, succinic acid anhydride, hymic acid anhydride and citraconic acid anhydride are useful for preparation of the compound of Formula VI.

Still also, the typical compounds of the formula:

R 0 CH i lOH are acrylic acid and methacrylic acid.

The present invention includes a coating composition comprising a prepolymer in which the base copolymer further comprises a vinyl monomeric polymerization unit C different from the polymerization units A and B. The unit C may be selected from monovinyl aromatic compounds such as styrene, a-methyl styrene, p-chlorostyrene and vinyl toluene; ethylenically unsaturated nitriles such as acrylonitrile, methacrylonitrile and amethylene glutaronitrile; aliphatic vinyl esters such as vinyl acetate and vinyl propionate; vinyl chloride, vinylidene chloride, allyl chloride, methallyl chloride, acrylamide, methacrylamide, N-butoxymethyl acrylamide, diacetone acrylamide, acrylic acid, methacrylic acid and methyl maleate. The selection of the unit C may be carried out from consideration of coating properties to be produced in the coating film by radiation curing. Preferably, the prepolymer comprising the polymerization unit C consists of l to 50% by weight of the unit A, 30 to 99% by weight of the unit B and at most 69% by weight of the unit C. Also, the polymerization unit C may be selected from vinyl monomers having a tertiary amine group such as compounds of the Formula IV:

, R IV wherein R R -R and p are the same as defined hereinbefore, respectively, N-dimethyl acrylamide, N-dimethyl methacrylamide, 2-vinyl pyridine, Z-methyl-S-vinyl pyridine, 3-ethyl-5-vinyl pyridine, 5-butyl-2-vinyl pyridine, and the like.

In case the base copolymer comprises the polymerization unit C selected from the vinyl monomers having a tertiary amine group, the base copolymer may further comprise a polymerization unit D selected from vinyl monomers different from the polymerization units A, B and C. In such case, preferably, contents of the polymerization units A, B, C and D in the base copolymer are 1 to 50, 30 to 99, 0.5 to 20 and at most 68.5% by weight, respectively.

The polymerization unit D may be selected from monovinyl aromatic compounds such as styrene, a-methyl styrene, .p-chlorostyrene, and vinyl toluene; ethylenically unsaturated nitriles such as acrylonitrile, methacrylonitrile and tat-methylene glutaronitrile; aliphatic vinyl esters such as vinyl acetate and vinyl propionate; vinyl chloride, vinylidene chloride, allylchloride, methallyl chloride, acrylamide, methacrylamide, N-butoxymethyl acrylamide, diacetone acrylamide and methyl maleate.

Usually, the coating composition of the present invention may be cured using an electron beam accelerator under condition wherein the accelerating voltage is 0.1 to 2.0 kev., and dose rate of the electron beam is 0.1 to 20 mrad/sed.

Also, the coating composition of the present invention may be cured by the irradiating of light having a wavelength of 2000 to 8000 A.

In case the coating composition is cured by light, a photo-polymerization sensitizer such as azo-type compounds, th'iuram-type compounds, peroxides, and carbonyl compounds, preferably, benzoin, benzoin methyl ether, anthraquinone and their derivatives should be added to the coating composition in order to accelerate the curing reaction.

The coating composition of the present invention can be applied to various uses by itself or in an enamel form in which the coating composition is mixed with some coloring materials such as dyestuif, pigment, metallic powder and the like. a

The base materials suitable for applying the coating material of the present invention are inclusive of metal, concrete, asbestos, and glass materials and materials unpreferable for heating to a high temperature, such as paper, plastics, natural fibers, synthetic fibers, soft fiber boards and hard fiber boards.

As is clear in the above illustration, the coating compositions of the present invention are suitable for radiation curing by irradiating electron beams, ultra-violet rays and the like, and for providing various film coatings having excellent coating features.

Various practices of the present invention are illustrated by the following examples. These examples are intended merely to illustrate the present invention and not in any sense to limit the manner in which the present invention can be practiced.

The parts and percentages recited therein and all through this specification, unless specifically provided otherwise, refer to parts by weight and percentage by weight.

EXAMPLE 1 Preparation of base copolymer (I) A mixture containing 25 parts by Weight of 2-hydroxyethyl methacrylate, 20 parts of methyl methacrylate, 35 parts of styrene, 20 parts of n-butyl acrylate, 3 parts of t-dodecyl mercaptane, 2 parts of azo-bis-isobutylonitrile and 10 parts of methanol was charged into a screw-type 1 1 EXAMPLE 2 Preparation of base copolymer (II) A mixture containing 25 parts of methyl-(Z-hydroxyethyl) maleate, 20 parts of methyl methacrylate, 35 parts of styrene, 20 parts of n-butyl acrylate, 3 parts of tdodecyl mercaptane, 2 parts of azo-isobutylonitrile and 10 parts of methanol was subjected to the same polymerization indicated in Example 1. The resultant base copolymer (II) had an average molecular weight of approximately 7,500.

EXAMPLE 3 Preparation of base copolymer (III) A mixture containing 30 parts of methyl-(Z-hydroxyethyl)itaconate, 30 parts of methyl methacrylate, 20 parts of n-butyl methacrylate, 3 parts of t-dodecyl mercaptane, 2 parts of azo-bis-isobutylonitrile, and 10 parts of methanol was subjected to the same polymerization indicated in Example 1. The resultant base copolymer (III) had an average molecular weight of approximately 9,000.

EXAMPLE 4 Preparation of base copolymer (IV) A mixture containing 30 parts of 2-hydroxyethyl acrylate, 20 parts of styrene, 20 parts of methyl methacrylate, 30 parts of 2 ethylhexyl methacrylate, 3 parts of ndodecyl mercaptane, 4 parts of benzoyl peroxide and 10 parts of methanol was polymerized in the same manner stated in Example 1. The resultant base copolymer (IV) had an average molecular weight of approximately 7,000.

EXAMPLE 5 Preparation of base copolymer (V) A mixture containing 35 parts of 2 hydroxypropyl methacrylate, 20 parts of methyl methacrylate, 40 parts of n-butyl methacrylate, 5 parts of dimethylaminoethyl methacrylate, 3 parts of t-dodecyl mercaptane, 2 parts of azo-isobutylonitrile and parts of methanol was polymerized in the same manner stated in Example 1. The resultant =base copolymer (V) had an average molecular weight of approximately 8,000.

EXAMPLE 6 100 parts of the base copolymer (I) described in Example 1 was dissolved in a solvent mixture containing 100 parts of methyl methacrylate, 50 parts of styrene and 0.05 part of hydroquinone monomethyl ether. Further, parts of maleic anhydride and 5 parts of dimethylaminoethyl methacrylate were added into the solution. The resultant solution was heated at 90 C. for 2 hours in order to additionally react maleic anhydride with the base copolymer (I). Through the additional reaction, 95% of the hydroxyl groups of the base copolymer (I) were esterified with the maleic anhydride. Next, 30 parts of glycidyl methacrylate were further added into the reaction solution and the reaction solution was heated at 90 C. for 4 hours. Through the second additional reaction, all of the carboxyl groups of the esterified base copolymer was esterified by the epoxy groups of the added glycidyl methacrylate. The degrees of esterifications were determined by an acid value measurement. The resultant copolymer composition was applied to a printed hard board with a thickness of 100p, and radiated with electron rays under a condition wherein accelerating voltage was 300 kw., electric current 20 ma., dose rate 3 mrad/sec. The film coating on the board was suficiently cured at a dosage of 6 mrad. The resultant film coating had high gloss, excellent organic solvent resistance, excellent boiling water resistance and excellent weathering resistance.

EXAMPLE 7 100 parts of the base copolymer (II), as described in Example 2, was dissolved into a solvent mixture containing 50 parts of n-butyl methacrylate, 50 parts of Z-ethyl hexyl acrylate, 70 parts of vinyl toleune and 0.05 part of hydroquinone monomethyl ether. 15 parts of succinic acid anhydride and 5 parts of dimethyl aminoethyl methacrylate were added to the solution. The reaction solution was heated at 100 C. for 1 hour in order to carry out the primary esterifying reaction of the base copolymer (II). After the first esterifying reaction, 20 parts of glycidyl acrylate were further added to the reaction solution, and the added reaction solution was further heated at 100 C. for 3 hours in order to secondarily esterify and/or etherify the firstly esterified base copolymer. The resultant composition was coated on the surface of a steel panel and the film coating thus formed was radiated under the same conditions stated in Example 6.

The film coating was sufiiciently cured at a dosage of 4 mrad.

EXAMPLE 8 100 parts of the base copolymer (III), as described in Example 3, was dissolved into a solvent mixture containing 150 parts of benzyl methacrylate and 0.05 part of hydroquinone monomethyl ether, and then 20 parts of itaconic acid anhydride and 5 parts of 2-methyl-5-vinyl pyridine were added to the solution. The reaction solution was heated at 100 C. for 2 hours in order to firstly esterify the base copolymer (III). Next, 20 parts of allyl glycidyl ester were added into the primary esterifying reaction solution and the added reaction solution was further heated at 100 C. for 3 hours in order to seeondly esterify and/or etherify the firstly esterified base copolymer. 100 parts of the resultant composition was mixed with 2 parts of benzoin methyl ether in order to obtain a coating composition. The coating composition was coated on the surface of a glass plate and the film coating was radiated with ultraviolet rays for 1 minute at a position just below 10 cm. from a high pressure mercury arc lamp having a dominant wave-length of 3600 A. and a power of 800 w. From the radiation, the film coating was sutficiently cured.

EXAMPLE 9 100 parts of the base copolymer (IV) described in Example 4 was dissolved in a solvent mixture containing 100 parts of ethyl acetate and 100 parts of toluene, and then 0.05 part of h'ydroquinone monomethyl ether, 25 parts of maleic acid anhydride and 5 parts of dimethyl aminomethyl methacrylate were added to the solution.

The solution was heated at C. for 4 hours to firstly esterify the base copolymer (IV). Next, 40 parts of glycidyl methacrylate and 3 parts of dimethyl aminoethyl methacrylate were added to the primary esterit'ying reaction solution, and the added reaction solution was further heated at 75 C. for 8 hours to secondly esterify and/or etherify the firstly esterified base copolymer (IV).

Finally, 0.5% of anthraquinone was added to parts of the resultant reaction solution in order to prepare a coating composition. The coating composition was applied on the surface of an aluminum plate with a thickness of 20a, by way of spray coating and dried by blowing hot air of 50 C. thereon. The film coating formed on the aluminum plate surface was cured by ultra-violet rays for 3 minutes under the same conditions described in Example 8, and was satisfactorily fixed to the aluminum plate surface.

The cured film had an insolubility of 92% by weight with respect to acetone.

EXAMPLE 10 A solution of 100 parts of the base copolymer (V) described in Example 5, 100 parts of cyclohexyl methacrylate, 70 parts of styrene and 0.05 part of hydroquinone monomethyl ether was prepared, 25 parts of maleic acid anhydride was added to the solution and the added reaction solution was heated at 100 C. for 1 hour in order to firstly esterify the base copolymer (V). 75 parts of ethylene glycol and 25 parts of succinic acid anhydride were further added to the reaction solution and the re- EXAMPLE 12 action solution was heated at 100 C. for 2 hours in order to continue the first esterifying. Next, 70 parts of glycidyl A solution of 100 parts of the base copolymer (IV), methacrylate and 0.05 part of hydroquinone monomethyl as indi a d in E a ple 4, in a S lv nt mixtur C ntainether were further added to the reaction solution and the ing 30 parts of Z-hydroxyethyl methacrylate, 200 parts of reaction solution was heated at 90 C. for 5 hours in order benzyl methacrylate and 0.1 part of hydroquinone monoto secondly esterify and/or etherify the firstly esterified methyl ether was prepared. 46 parts of succinic acid anbase copolymer (V). hydride and parts of dimethylaminoethyl methacrylate The resultant reaction product mainly comprised a cowere added to the solution and the solution was heated at polymer having a unit structure of the formula 10 90 C. for 3 hours in order to firstly esterify the base and a polymerizable compound of the formula:

0H 0 0H 0 oH,=0-g-oCH,-( :H-GHI-O-g-CH OH,g-o-cH,oH,-o -o11,GHlfi-OAJHPoH-Qm-O -C=CH,

The resultant composition was applied on the surface copolymer (IV). 70 parts of glycidyl methacrylate were of a steel plate so as to form a film coating of 50p thickfurther added to the reaction solution and the solution mess. The film coating was radiated by electron rays in was heated at 90 C. for 6 hours to secondly esterify a nitrogen atmosphere under the same conditions stated and/or etherify the firstly esterified base copolymer. The in Example 6 and was sutficiently cured at a dosage of resultant reaction product mainly contained a copolymer 3 mrad. having a unit structure of the formula:

-CHg-CH (llHz J-ooH-( 3H 0 on CH: 0 o(i-CH2CH,o-o-CH2CH-CH,00J:-0H, and a polymerizable compound of the formula: $H3 (EH3 GH -1C-fiJ-O-CH CH -O-fi-CH CH fi-O-CH CHCH -OCC=CH; 0 0 0 H 0 EXAMPLE 11 The film coating of the above-stated reaction product, (1) Preparation of base copolymer (VI) tihoast 1s, :foagtmg cctlamposlrtion wss sufficiently cured at a A base copolymer (VI) having an average molecular age mm 0 e as r H weight of approximately 9,000 was prepared from 30 parts EXAMPLE 13 of Z-hydroxyethyl methacrylate, 30 parts of methyl methacrylate, 15 parts of monomethyl itaconate, 25 parts of methacrylonitrile, 3 parts of t-dodecyl mercaptane, 2 parts of azo-isobutylonitrile and 10 parts of methanol in the same polymerization conditions stated in Example 1.

A solution of 100 parts of the base copolymer (IV), as stated in Example 4, 200 parts of benzyl methacrylate and 0.1 part of h'ydroquinone monomethyl ether was prepared. Then, 23 parts of succinic acid anhydride and 10 parts of dimethylaminoethyl methacrylate were added to (2) Preparation of coating composition (11-1) the solution and the solution was heated at 90 C. for 3 hours to firstly esterify the base copolymer (IV). Next A solution 100 arts of the base co o1 mer 50 100 Parts of g glethacrylate, 50 gg parts of methacryltc acid and 118 parts of glycidyl methlate were further added to the solution and then the and 0.05 part of hydroqumone monomethyl ether were acry 0 prepared. 40 parts of hymic acid anhydride and 5 parts of added reacting sqhmon was at 90 for 6 f dimethylaminoethyl methacrylate were added to the sohb to secondly estenfy and/or etherify the firstly esterified tion. The added reaction solution was heated at 90 C. for a d h 2 hours to firstly esterify the base copolymer (VI). Next, resu z' p i at coatmg 30 parts of glycidyl methacrylate were further added to i contame p0 ymenza 6 compound of the the reaction solution, and the added reaction solution was heated at 90 C. for 4 hours to secondly esten'fy and/ or H H etherify the firstly esterified base copolymer (VI). Thus, 011 :0-

a coating composition (11-1) was obtained.

A film coating of the coating composition (11-1) was H Q sufiiciently cured by the same radiation manner, as stated T film coatmg of the resultant cOHIPOSIUOII Was in Example 10 at a dosage f 4 mracL ficlently cured at a dosage of 2.5 mrad of electron beams.

(3) Preparation of coating composition (11-2) EXAMPLE 14 A coating composition (11-2) was prepared from 100 A sQlution of 100 Parts of the base copolymer as parts of the Ibase copolymer and the ame component stated 111 Example 5, 150 parts 0f benzyl methacrylate and as indicated in section (2) of the present example, except 50 Parts Of a mon m r f the formula: that 35 parts of hexahydrophthalic acid anhydride relaced the h mic acid anh dride as a first esterif in a ent, II it the same manner as i dicated in section (2 g g C CHFCH2 $H The film coating of the coating composition (11-2) was 006111 000011: sufiiciently cured by the same manner, as stated in Exand 0.1 part of hydroquinone monomethyl ether was ample 10, at a dosage of 6 mrad. prepared. 23 parts of succinic acid anhydride were added to the solution and the solution was heated at 90 C. for acting solution, 130 parts of Z-hydroxyethyl meth- 3 hours to esterify the base copolymer (V). Next, 29 parts acrylate, 300 parts of toluene and 2 parts of p-tolueneof succinic acid anhydride and 105 parts of glycidyl sulfonic acid were added and heated at 110 C. for 5 methacrylate were further added to the solution. The sohours for dehydrocondensation of the added components lution was heated at 90 C. for 6 hours to secondly esteri- 5 with distillation of 16.0 parts of condensation water. The fy and/or etherify the firstly esterified base copolymer. resultant condensation product was treated in the same The resultant reaction product, that is, coating commanner as stated in Example 16 and thus, a liquid mainposition was coated on a steel plate surface and sufliciently 1y containing a compound of the formula:

CH3 (EH3 GHFJ-gF-O-GILOH 0-J-CH.(JH=fi-ooH cH,o?-o=oH, 0

cured at a dosage of 4 mrad of electron rays under the was obtained. A coating composition was prepared from same conditions as indicated in Example 6. 40 parts of the liquid compound and 60 parts of the reaction product of Example 7, and then coated on a steel EXAMPLE 15 panel and cured in the same manner stated in Example The film coatin was sufiiciently cured at a dosa e of A coating composition was prepared in the same man- 7 g g net as indicated in Example 14 from 100 parts of the 3 mrad of electron beams. The cured film had a h gh base copolymer (VI); a mixture of 250 parts of benzyl 2O adhesiveness to the steel surface and an excellent immethacrylate and 0.1 part of hydroquinone monomethyl Pact resistance ether; a primary esterifying agent containing 23 parts EXAMPLE 18 0f SUCCiIlic acid anhydride and 10 Parts of q l y After 98 parts of maleic acid anhydride and 130 parts ethyl methacl'ylate; and a Secondary esterlfylng agent of of 2-hydroxyethyl methacrylate were reacted in the same 35 parts of glycidyl methacrylate. manner stated in Example 16, 38 parts of 1,3-butylene After the reactions were completed, an acid value of l l, 400 parts f toluene d 3 parts of q l lthe reacting solution was approximately zero. fonic acid were added to the reaction solution and treated The film coating of the resultant composition was sufi th am manner tated in Example 16, A a re ult of ficienfly Cured at a dosage of 5 mrad 0f e ron beams the treatment, a transparency liquid mainly containing in the same manner as stated in Example 6. a compound of the formula:

OH: O CH: a O O CH =(i)-iI-OOH2CHaOgCH=GH-i3OCH CH JH-O-CCH=CH O(JH;;t.'3HIi-0( J&=CH

EXAMPLE 16 5 was obtained. A mixture of 130 parts (1 mol equivalent), of A coating composition was prepared from 30 parts droxyethyl acrylate, 100 parts (1 mol equivalent) of of the resultant liquid and 70 parts of the reaction product succinic acid anhydride and 0.5 parts of hydroquinone obtamed ExatlPle .coated 9 3 Steel plate so as monomethyl ether was charged into a reactor filled with form a film coatmg havuig a thlckness of 3 nitrogen gas and heated at 1300 for 20 minutes 97 40 ated by electron beams in the same manner indicated parts (1 mol equivalent) of bisphenol A, 400 parts of in Example 7. The film coating was sufiiciently cured at toluene and 3 parts of p-toluenesulfonic acid were further a i of The cured had f excellent added into the reactor and the reaction solution was fiemblllty, adh?slveness to Steel Impact reslstance and heated at a reflux temperature for 4 hours. Thus, 15.5 weathenng resistance partsof condensation water were distilled oft from the EXAMPLE 19 reaction system. The resulted reaction solution was neutralized to a pH 7 by addition of sodium bicarbonate. To a reaction solution obtained by a reaction of 130 Then, p-toluenesulfonic salt was precipitated. After the parts of 2-hydroxyethyl methacrylate and 100 parts of precipitate was filtered, toluene in the solution was evaposuccinic acid anhydride, 31 parts of ethylene glycol, 400 rated and a transparency mainly containing a liquid comparts of toluene and 3 parts of p-toluenesulfonic acid pound of the formula; were added and subjected to the same treatment stated was obtained. The compound had a viscosity of T which in Example 16. Thus, a reaction liquid mainly containwas determined by way of a Gardner-Holdt bubble vising a compound of the formula:

cometer. A coating composition was prepared from 70 was obtained. parts of the composition stated in Example 6 and 30 A coating composition (19-1) was prepared from 40 parts of the above-stated composition and coated on parts of the above-obtained liquid and parts of the a steel plate surface so as to form a film coating having composition Stated in Example d Coated a thickness of 3011.. on a steel plate surface. The film coating was sufliciently cured at a dosage The film Coating was sufiicienfly cuYed at a dosage of f Z mr d of l tr rays, 2.5 mrad of electron beams. The cured film had excellent EXAMPLE 17 impalct resistance, flexibility and adhesivenes to the steel pane 130 parts of Z-hydroxyethyl methacrylate and 100 Also, a coating composition (19-2) was prepared from parts of succinic acid anhydride were reacted in the same 40 parts of the above-obtained liquid and 60 parts of manner as stated in Example 16. To the resultant rethe composition 11-2) stated in Example 11, and coated 18 on a steel panel. The film coating was sufficiently cured A coating composition was prepared from 30 parts of at a dosage of 3 mrad of electron beams. The cured the resultant liquid and 70 parts of the composition illusdilm had excellent features. trated in Example 7, and a film coating of the coating EXAMPLE 20 composition was sufliciently cured at a dosage of 5 mrad 5 of electron beams in the same manner indicated in Example 18. The cured film had an excellent hardness, adhesiveness to a hard board and weathering resistance.

A mixture of 188 parts of methyl-(Z-hydroxyethyl) itaconate, 98 parts of maleic acid anhydride, 2 parts of dimethylaminoethyl methacrylate and 0.1 parts of hydroquinone monomethyl ether was charged into a reactor and heated at 100 C. for 1 hour. A mixture of 149 parts EXAMPLE 23 of glycidyl methacrylate and 1 part of dimethylaminoethyl methacrylate was further charged into the reactor 146 Parts of adlplc acld, 298 Parts of g y y meth' and heated at 100 C. for 5 hours. From the reaction, 'y 3 Parts of dimethylaminoethyl methacrylate and a liquid mainly containing a compound of the formula: 0.1 part of hydroquinone monoethyl ether were mixed 0 i l-0011a CH2: (1H,

H,-fi-O-OHflH O-fi-cH=cH(f0CHz0H-0H,-0- i0=0H,

o 0 H was obtained. and then heated at 100 C. for 5 hours and a liquid A coating composition was prepared from 30 parts of mainly containing a compound of the formula:

CH; CH; CH= -fi-o-CHz-CHCH2 2)lfiO-CH1CHCH3O-? =CH,

0 H 0 the above-stated liquid and 70 parts of the composition was obtained. indicated in Example 17 and coated on a steel panel A coating composition was prepared from 70 parts of surface. The film coating was sufficiently cured at a the resultant liquid and 30 parts of the composition illusdosage of 2.5- mrad of electron beams. The cured film 30 trated in Example 6, and a film coating of the coating had high hardness and excellent weatherin resistance. composition was sufiiciently cured at a dosage of 1.5 mrad EXAMPLE 21 of electron beams. The cured film had excellent hardness, adhesiveness to a hard board and weathering resistance. 174 parts of methyl-(Z-hydroxyethyl) maleate and 98 EXAMPLE 24 parts of maleic acid anhydride were subjected to an addi- 5 tion reaction in the same manner indicated in Example 128 parts of glycidyl acrylate, 72 parts of acrylic acid and 120 parts of allyl glycidyl ether were further and 2 parts of dimethylaminoethyl methacrylate were added to the resultant reaction solution. The reaction mixed and then heated at 100 C. for 5 hours in reactor. mixture was treated in the same manner described in parts of the resultant product and 70 parts of the com- Example 20 and a liquid mainly containing a compound position illustrated in Example 6 were mixed and a coatof the formula: ing composition resulted. A film coating of the coating CH-i JOCHs CHCO-CH CH -O(|lJ-CH=CH-fiOCH,CH-CH -CH=GH;

i 0 0 H was obtained. composition formed on a hard board was irradiated by A coating composition was prepared from 30 parts of electron beams at a dosage of 2.5 mrad. A completely the obtained liquid and 70 parts of the composition in hardened film having excellent hardness, weathering redicated in Example 6, and a film coating formed on a sistance and chemical resistance property was obtained.

printed hard board was cured at a dosage of 4 mrad of EXAMPLE 25 electron beams in the same manner indicated in Example 16, Th cured fil h d hi h h d 142 parts of glycidyl methacrylate, 100 parts of succinic acid anhydride, 1 part of dimethylaminoethyl meth- EXAMPLE 22 acrylate and 0.05 part of hydroquinone monomethyl 108 parts of neopentyl glycol, 186 parts of maleic acid ether was charged into a reactor together with a small anhydride, 3 parts of dimethylaminoethyl methacrylate quantity of water and heated at 100 C. for 6 hours. The

and 0:1 part of hydroquinone monomethyl ether were reaction resulted in a composition product mainly conmixed and then heated at 100 C. for 2 hours in a retaining a compound of the formula:

l r-$2. l

actor. To the mixture, 298 parts of glycidyl methacrylate, wherein q is an average number of 2.

1 part of dimethylaminoethyl methacrylate and 0.1 part A coating composition was prepared from 50 parts of of hydroquinone monomethyl ether were added and the the resultant product and 50 parts of the composition ilreaction mixture was further heated at 100 C. for 5 lustrated in Example 7, and formed into a film coating hours. Thus, a composition mainly containing a comon a steel plate surface. The film coating was irradiated pound of the formula: by electron beams at a dosage of 1.5 mrad and thus suf- CH: CH3 CH3 CHF -%-OCHg-C-CH-0?CH=CHCOCH3-+-CH1OCCH=CH 'COCH CHCH1OC =0H,

0 H OH: H

was obtained. ficiently cured. The cured film had excellent adhesiveness to a steel panel, excellent hardness and chemical resistance property.

EXAMPLE 26 An unsaturated alkyd resin was obtained from 62 parts of ethylene glycol and 49 parts of maleic acid anhydride and 73 parts of adipic acid.

A coating composition was prepared from 30 parts of the obtained unsaturated alkyd resin and 70 parts of the composition illustrated in Example 7, coated on a steel panel so as to form a film coating. The film coating was irradiated at a dossage of 4 mrad by electron rays in the same manner indicated in Example 7, and thus sufiiciently cured. The cured film had excellent adhesiveness to a steel panel hardness, excellent impact resistance and weathering resistance.

What is claimed is:

1. A coating composition comprising a prepolymer containing the following components,

(1) a base copolymer having an average molecular weight of 1,000 to 100,000 and comprising-the following units,

(a) polymerized units A of at least one vinyl monomer having a hydroxyl group selected from the group consisting of allyl alcohol, methallyl alcohol, hydroxyalkyl acrylamide, hydroxylalkyl methacrylarnide and compounds of the formula I, II, and III,

in which N, R and R each represents a hydrogen atom or methyl group, R represents R R H or CH E-O l D In in which R represents a hydrogen atom or methyl group and n represents an integer of 1 10, R represents a hydrogen atom or alkyl group of 1 to 12 carbon atoms, and m is 1 or 2,

(b) polymerized units B of at least one ogfi-ethylenically unsaturated carboxylic acid ester of a monohydric alcohol having 1 to 18 carbon atoms,

(2) at least one polybasic carboxylic acid anhydride which initially esterifies at least mol percent of said hydroxyl groups of said base copolymer with the carboxyl group thereof, and

(3) at least one epoxy vinyl monomer selected from the group consisting of glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, methallyl glycidyl ether or vinyl cyclohexene monooxide, said epoxy vinyl monomer subsequently esterifying and! or etherifying at least 10 mol percent of the total content of said hydroxyl group and carboxyl group of said initially esterified base copolymer with the epoxy group thereof.

2. A coating composition as claimed in claim 1 wherein said base copolymer also includes polymerized units C of at least one compound selected from the group consisting of styrene, a-methylstyrene, o-, m-, or p-chlorostyrene,

20 vinyl toluene, acrylonitrile, methacrylonitrile, oz-methylene glutaronitrile, vinyl acetate, vinyl propionate, vinyl chloride, vinylidene chloride, allyl chloride, methallyl chloride, acrylamide, methacrylamide, N-butoxymethylacrylamide, diacetone acrylamide and basic vinyl compounds of the Formula IV:

R Iv

wherein R represents a hydrogen atom or methyl group, R and R" represent a methyl or ethyl group, and p is 1 or 2, N-dimethyl acrylamide, N-dimethyl methacrylamide, 2-vinyl pyridine, Z-methyl-S-vinyl pyridine, 3-ethyl-5-vinyl pyridine and 5-butyl-2-vinyl pyridine, said polymerized units C being diiferent from said polymerized units A and B.

3. A coating composition as claimed in claim 2, wherein said base copolymer further comprises polymerized units D diiferent from said polymerized units A, B and C, and wherein said polymerized units D are of at least one compound selected from the group consisting of styrene, ot-methyl-styrene, 0-, m-, or p-chlorostyrene, vinyl toluene, acrylonitrile, methacrylonitrile, lat-methylene glutaronitrile, vinyl acetate, vinyl propionate, vinyl chloride, vinylidene chloride, allyl chloride, methallyl chloride, arylamide, methacrylamide, N-butoxymethylacrylamide and diacetone acrylamide.

4. A coating composition as claimed in claim 1, where in the contents of said polymerized units A and B in said base copolymer are 1 to 50 and 50 to 99% by weight, respectively.

5. A coating composition as claimed in claim 2, wherein the contents of said polymerized units A, B and C in said base copolymer are 1 to 50%, 30 to 99% and at most 69% by weight, respectively.

6. A coating composition as claimed in claim 3, wherein the contents of said polymerized units A, B, C and D in said base copolymer are 1 to 50, 30 to 99, 0.5 to 20 and at most 68.5% by weight, respectively.

7. A coating composition as claimed in claim 2, wherein the contents of said polymerization units A, B and C in said base copolymer are 1 to 50, 30 to 99 and 0.5 to 20% by weight, respectively.

8. A coating composition as claimed in claim 1, wherein said polymerized units B are derived from esters of (1) acrylic acid, methacrylic acid, itaconic acid or a-methylene glutaric acid and (2) straight or branched chain monohydric alkyl alcohol of 1 to 18 carbon atoms, cyclohexanol, benzyl alcohol, phenethyl alcohol, ethylene glycol mono-alkyl ether, or propylene-glycol mono-alkyl e er.

9. A coating composition as claimed in claim 1, wherein the polybasic carboxylic anhydride 2) is an anhydride of maleic acid, chlorinated maleic acid, succinic acid, itaconic acid, tat-methylene glutaric acid, citraconic acid, phthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, naphthalene dicarboxylic acid, dodecyl succinic acid, or 1,4,5,6,7,7-hexachloro-bi-cyclo(2,2,1)-hept-5-en-2,3 di. carboxylic acid.

A process for preparing a coating composition com- PI'lSlllg (1) copolymerizing a mixture of (a) at least one vinyl monomer having a hydroxyl group selected from the group consisting of allyl alcohol, methallyl alcohol, hydroxyalkyl acrylamide, hydroxyalkyl methacrylamide and compounds of the Formula I, II, and III,

GH=C RI oHi)moo-R-o-R,

and

in which R R and R each represents a hydrogen atom or methyl group, R represents in which R represents a hydrogen atom or methyl group and n represents an integer of 1 to 10, R represents a hydrogen atom or alkyl group of 1 to 12 carbon atoms, and m is 1 or 2, and

(b) at least one 0:,5 ethylenically unsaturated carboxylic acid ester of a monohydric alcohol having 1 to 18 carbon atoms, to form a base copolymer having an average molecular weight of 1,000 to 100,000 and containing hydroxyl groups,

(2) reacting at least one polybasic carboxylic acid anhydride with said base copolymer dissolved in an organic solvent in a proportion of at least 0.1 mol of the anhydride per mol of the hydroxyl groups in said base copolymer, and

(3) subsequently reacting at least one epoxy vinyl monomer selected from the group consisting of glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, methallyl glycidyl ether or vinyl cyclohexene monooxide with the resultant copolymer of step (2) in a proportion of at least 0.1 mol of said epoxy vinyl monomer per mol of the combined content of hydroxyl groups and carboxyl groups in the resultant copolymer of step (2).

11. A process as claimed in claim 10, wherein the proportions of said monomers A and B in said mixture are 1 to 50 and 50 to 99% by Weight, respectively.

12. A process as claimed in claim 10, wherein said monomer mixture in step (1) also comprises a polymerizable vinyl monomer C which is at least one compound selected from the group consisting of styrene, a-methylstyrene, 0-, m-, or p-chlorostyrene, vinyl toluene, acrylonitrile, methacrylonitrile, lX-IIlCthYlBHC glutaronitrile, vinyl acetate, vinyl propionate, vinyl chloride, vinylidene chloride, allyl chloride, methallyl chloride, acrylamide, methacrylamide, N-butoxymethyl-acrylamide, diacetone acrylamide and basic vinyl compounds of the Formula IV:

(IV) wherein R represents a hydrogen atom or methyl group, R and R represent a methyl or ethyl group, and p is 1 or 2, N-dimethyl acrylamide, N-dimethyl methacrylamide, 2-vinyl pyridine, 2-methyl-5-vinyl pyridine, 3-ethyl-5-vinyl pyridine and S-butyl-Z-vinyl pyridine, said vinyl monomer B being different from said monomers A and B.

(6H; CH (E-CHz-CHz-H C O O R O O R V 13. A process as claimed in claim 12, wherein the proportions of monomers A, B and C in said mixture are 1 to 50, to 99 and at most 69% by weight, respectively.

14. A process as claimed in claim 12, wherein said monomer mixture in step (1) further comprises a polymerizable vinyl monomer D different from said monomers A, B and C, said vinyl monomer D being at least one compound selected from the group consisting of styrene, a-methyl-styrene, 0-, m-, or p-chlorostyrene, vinyl toluene, acrylonitrile, methacrylonitrile, a-methylene glutaronitrile, vinyl acetate, vinyl propionate, vinyl chloride, vinylidene chloride, allyl chloride, methallyl chloride, arylamide, methacrylamide, Nbutoxymethyl-acrylamide and diacetone acrylamide.

15. A process as claimed in claim 14, wherein the proportions of monomers A, B, C and D in said mixture are 1 to 50, 30 to 99, 0.5 to 20%, and at most 68.5% by weight, respectively.

16. A process as claimed in claim 10, wherein the reactions of step (2) and (3) are accelerated by at least one basic vinyl monomer selected from a member of the group consisting of a compound of the Formula VII:

i) R IV wherein R represents a hydrogen atom or methyl group, R and R represent methyl or ethyl group, and p is 1 or 2, N-dimethyl acrylamide, N-dimethyl methacrylamide, 2-vinyl pyridine, Z-methyl-S-vinyl pyridine, 3-ethyl-5-vinyl pyridine or 5-butyl-2-vinyl pyridine.

References Cited UNITED STATES PATENTS 3,448,089 6/1969 Celeste 26078.5 T 3,620,990 11/1971 Cheswick et al 260-40 R WILLIAM H. SHORT, Primary Examiner E. WOODBERRY, Assistant Examiner U.S. Cl. X.R.

11793.31, 124, 126, 127, 138.8, 148, 2'04-l59.14, 159.15, 159.19; 26078.4 D, ED, 78.58 B, 78.5 T, 31.6, 861, 873 

